They also spent as little as one hour a day out of their rooms at weekends, falling well below the government target of five hours.
HMP Feltham covers two sites, one for boys under the age of 18 and one for adult males.
The report identifies significant concerns regarding the time prisoners were locked in their cells across both sites.
The document cites the reason for this, according to the prison, was staff absence.
It also noted boys were not receiving the target 15 hours of education a week and training provision for adults was unfit for purpose.
Inspectors say it’s disappointing news because the same issues were highlighted in a previous report.
But the Board says it is pleased to report that relationships between staff and boys in the YOI were observed to be excellent.
We’ve contacted the MoJ for comment.
